Just the community I needed to find! I was literally about to close lemmy to go look for open source games and ports for Android.
I started Shattered Pixel Dungeon and was having a lot of fun with it. It is the first real Roguelike I think I have gotten into. It takes a bit of learning, but it still feels pretty accessible. Definitely worth the free download to see if you enjoy it
So very similar vein, uses many of the same mechanics and a lot of the same framework is Pathos. I think it's really well fleshed out even though I haven't managed to get very far. Amazing depth and mechanics but initially it felt like running into a brick wall for me. But the tutorials are very easy to read in the game and you can tweak a lot to become a god in different ways so you can test out and try to understand mechanics. I think it's great fun and kinda like a deeper, grander Shattered Pixel Dungeon!
I have been a long-lasting Sauerbraten player, although I only play it occasionally due to the low player base.
Apart from that, I have been playing OpenTTD, Mindustry and other open strategic games and I am looking for similar games. I have played a lot of other open source games that do not come in my mind as of now, I have been using Linux as my main OS for quite a long time.